Magnetic encoder and method of manufacturing magnetic encoder

Abstract

A cylindrical portion of an annular support member has a small-diameter portion press-fitted to an inner ring of a bearing, and a large-diameter portion formed by enlarging a part of the cylindrical portion, which is closer to an inboard side than the small-diameter portion. An annular magnet member has an inner-diameter side recessed portion formed by depressing, toward an outboard side, a radially inner part of a surface, in an inboard side, of the annular magnet member, and a wraparound portion that wraps around the annular support member toward the outboard side to a stepped portion between the small-diameter portion and the large-diameter portion. An inner peripheral surface of the wraparound portion protrudes radially inward more than an inner peripheral surface of the small-diameter portion. An inner peripheral surface of the inner-diameter side recessed portion has a gate mark of an inner-diameter side disk gate.

The invention claimed is: 
     
         1 . A magnetic encoder for use in a wheel support bearing device of an automobile, the magnetic encoder comprising:
 an annular support member made of metal; and   
       an annular magnet member made of a plastic magnet,
 the annular support member includes:
 a cylindrical portion that fits on an exterior of an inner ring of a bearing of the wheel support bearing device; and 
 an outward flange portion extending radially outward from an end portion of the cylindrical portion in an inboard side, 
 
 the cylindrical portion has a small-diameter portion press-fitted to the inner ring of the bearing, and a large-diameter portion formed by enlarging a part of the cylindrical portion, the part being closer to the inboard side than the small-diameter portion, 
 the annular magnet member is attached to a surface of the outward flange portion in the inboard side, 
 the annular magnet member has an inner-diameter side recessed portion formed by depressing, toward an outboard side, a radially inner part in a surface, in the inboard side, of the annular magnet member, and a wraparound portion that wraps around the annular support member toward the outboard side to a stepped portion between the small-diameter portion and the large-diameter portion of the cylindrical portion, 
 an inner peripheral surface of the wraparound portion protrudes more radially inward than the inner peripheral surface of the small-diameter portion, the inner peripheral surface of the wraparound portion being press-fitted to the inner ring, 
 the inner peripheral surface of the inner-diameter side recessed portion has a gate mark of an inner diameter disk gate, and 
 a portion of the inner peripheral surface of the inner-diameter side recessed portion lies between the wraparound portion of the annular magnet member and the gate mark. 
 
     
     
         2 . A method of manufacturing a magnetic encoder for use in a wheel support bearing device of an automobile, wherein
 the magnetic encoder includes: an annular support member made of metal; and an annular magnet member made of a plastic magnet,   the annular support member includes:
 a cylindrical portion that fits on an exterior of an inner ring of a bearing of the wheel support bearing device; and 
 an outward flange portion extending radially outward from an end portion of the cylindrical portion in an inboard side, 
   the cylindrical portion has a small-diameter portion press-fitted to the inner ring of the bearing, and a large-diameter portion formed by enlarging a part of the cylindrical portion, the part being closer to the inboard side than the small-diameter portion,   the annular magnet member is attached to a surface of the outward flange portion in the inboard side,   the annular magnet member has an inner-diameter side recessed portion formed by depressing, toward an outboard side, a radially inner part in a surface, in the inboard side, of the annular magnet member, and a wraparound portion that wraps around the annular support member toward the outboard side to a stepped portion between the small-diameter portion and the large-diameter portion of the cylindrical portion,   an inner peripheral surface of the wraparound portion protrudes more radially inward than the inner peripheral surface of the small-diameter portion, the inner peripheral surface of the wraparound portion being press-fitted to the inner ring, and   a portion of an inner peripheral surface of the inner-diameter side recessed portion lies between the wraparound portion and a gate mark formed in the inner peripheral surface of the inner-diameter side recessed portion,   the method comprising:   
       molding the annular support member by one of (i) pressing and (ii) the pressing and cutting;
 applying a thermosetting adhesive to a part of or an entire of a joint surface of the molded annular support member with the annular magnet member; 
 opening an injection molding die and setting, in the injection molding die, the annular support member to which the thermosetting adhesive is applied, as an insert work; and 
 closing the injection molding die, and injecting a molten resin in a cavity of the injection molding die from an inner-diameter side disk gate of the injection molding die, to thereby mold the annular magnet member, the inner-diameter side disk gate being arranged at a position corresponding to the gate mark of the annular magnet member.